I know I asked myself what a “Loop Based Music Sequencer App” is so I will address that first. Spinfuse is a on device music sequencer, beat maker, and ringtone creator app which lets you create your own sounds for anything. I remember having a similar app on my Symbian phones way back in the day and I had some fun playing with Spinfuse.
The app lets you exchange sounds you create from your Spinfuse project and upload//download completed songs, loops, and ringtones. The app is going to have a web portal soon which is why there is a login for the app but that will come after the beta is completed.
If you wanted to have some fun creating MIDI like music on your BlackBerry check out the beta of Spinfuse at this link in their forums. You can download the app OTA at this link or for desktop installation at this link. The user guide for Spinfuse is available here. Its a pretty hefty app at over 1MB so watch out if you are on a limited data plan.